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Re: Altitude effects on hummingbird flight?

don ohmes writes:

Hummingbirds are the largest observed species using hovering, a
size-constrained locomotion; if some "un-related" group of similar size
evolved hovering, it seems to me that a high degree of convergence
would be expected. In either case, I wonder what could have knocked
them out? Given that hummers occur in Alaska, it astonishes me that
they never got a foothold in Asia. Anybody know got a clue?

Some (many?) extant hummingbirds seem to be highly specialist feeders, sometimes only feeding from a very limited number of flower species. Often those flower species themselves mostly get pollinated by hummers alone. If one species is reduced in number then the other may follow (if one or the other can't adapt to a new food source / pollinator). I can very easily envisage a feed-back spiral driving both into extinction in times of environmental stress.

The question really isn't why hummers from other parts of the world may have become extinct; perhaps the more interesting question is why such highly specialised species have managed to survive (and even thrive) in the Americas for so long. Specialists generally don't do so well during extinction events.


Dann Pigdon
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://heretichides.soffiles.com